(a) Field of the Invention
This inventive concept relates to semiconductor technology, more specifically, a semiconductor device and its manufacturing method.
(b) Description of the Related Art
NOR flash memory has been widely used in embedded systems to read and write programs. Compared to NAND flash memory, NOR flash memory provides better performance on data reading and writing, and supports in-chip data processing with eXecute-In-Place (XIP).
However, as the density of memory units in a NOR flash memory increases, the thickness of a tunnel oxide layer in the NOR flash memory may go out-of-spec in some regions, which in turn increases a threshold voltage of the NOR flash memory in those regions.